This invention relates to a reduction kiln gas-on system, and in particular to the assembly of the gas pipe and also of the cooling air pipe in conjunction with a means of supporting the system remote from the supported inner end of the gas pipe to thereby reduce the deflection stress in the gas pipe which occurs due to the misalignment between the rotary kiln and the stationary housing portions associated with the kiln and also eliminates cooling process air leakage into the combustion chamber of the kiln.